A wide variety of stands are utilized in the entertainment industry, as well as in other fields, for supporting microphones (xe2x80x9cmicsxe2x80x9d), speakers, lighting, musical instruments, music scores, etc. The industry standard for a mic stand employs a round, sand-cast base that measures about 10 inches in diameter and weighs about six pounds, with which a shaft is threadably assembled. The shaft will usually consist of two telescoping tubular sections operatively interengaged by a center clutch for permitting height adjustment, the most widely used form of clutch being operated by rotation of a collar attached to the lower shaft section.
Albeit a convenient and practical arrangement, there is a chronic tendency for operation of a rotary clutch to cause disengagement (i.e., loosening) of the shaft from the base. The same annoyance would of course be inherent in other assemblies in which a shaft or post is engaged with a base by a movement having a significant rotational component.
Accordingly, it is a broad object of the present invention to provide a novel stand assembly, and a novel base suitable for use therein, wherein and whereby inadvertent disengagement is prevented by means of an automatically operating anti-rotation feature.
It is also an object of the invention to provide such a stand assembly and base wherein and whereby assembly and disassembly are quick and easy, and wherein there is no need for any supplemental manual fastener, such as a conventional thumbscrew and cooperating dimple or crease arrangement.
It has now been found that certain of the foregoing and related objects of the invention are attained by the provision of a stand assembly comprised of a ground-engaging base, a shaft, and means for attaching the shaft to the base. The means for attaching will include a normally upwardly opening base aperture (i.e., an aperture that opens upwardly when the base is resting on the ground), an end portion of the shaft that is dimensioned and configured for engagement within the base aperture, and automatically operating anti-rotation means for inhibiting relative rotation between the shaft and the base, and thereby for preventing inadvertent disengagement.
In one embodiment the end portion of the shaft and the sidewall defining the base aperture will be matingly threaded, preferably with a pitch that provides no more than twelve, and more advantageously fewer than twelve, threads per inch. A ratchet mechanism, effective for releasably interengaging the shaft against unscrewing from the base member, will advantageously provide the anti-rotation means, which mechanism with desirably be foot-operated for release. The shaft will usually comprise a plurality of telescopically interengaged sections, and clutch means for releasably affixing the sections in positions of relative extension, the latter including an operating member that is disposed on the shaft sections and is rotatable in the direction of unscrewing of the shaft from the base, for release of the sections for relative telescopic movement. In addition, the shaft (and/or the aperture-defining sidewall structure of the base) may have means thereon defining a ramp surface that is inclined outwardly of the aperture and toward the axis of the shaft, for cooperation with an element on the sidewall structure (and/or on the shaft) that is constructed and disposed for engaging the ramp surface, with the shaft and base in the xe2x80x9crelativexe2x80x9d orientation, and for producing a wedging action as the shaft is urged outwardly of the aperture by the biasing means.
Alternative anti-rotation means may comprise a locking arrangement having features that permit shaft insertion in one orientation relative to the base, and that lock the shaft in a second orientation, the respective shaft orientations being displaced from one another by an angular distance no greater than one-half turn of the shaft (i.e., 180xc2x0), and preferably no greater than one-quarter turn. Such a locking arrangement may more specifically comprise a continuous groove extending along the sidewall of the base member aperture, and a stud projecting laterally (i.e., radially) from the shaft and dimensioned and configured for slidable engagement in the groove. An entrance section of the groove extends inwardly into the base member from the mouth of the aperture, and a blind section of the groove, connected to an inner end of the entrance section, extends generally outwardly toward the aperture mouth but terminates short thereof; the groove may, for example, advantageously be of generally J-shaped configuration. Such a locking arrangmenet will usually additionally include biasing means operatively disposed for urging the shaft outwardly of the aperture.